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Hypothyroidism in Dogs: Causes, Symptoms, and Effective Treatments

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Written by Nick Peplow


Dogs, like humans, can suffer from various health issues, including hypothyroidism. This condition occurs when the thyroid gland doesn’t produce enough thyroid hormone, leading to a range of symptoms that can significantly impact your dog’s quality of life.

Common symptoms of hypothyroidism in dogs include lethargy, weight gain, hair loss, and a dull coat. Other signs may include increased susceptibility to infections, especially of the skin and ears. If you notice these changes in your dog, it’s crucial to consult your veterinarian for a proper diagnosis and treatment plan.

Causes of hypothyroidism often stem from the immune system attacking the thyroid gland or other underlying conditions. Diagnosis typically involves a series of blood tests. The good news is that treatment is straightforward and involves daily medication to replace the missing hormone. Proper management ensures that your dog can live a healthy, happy life despite their diagnosis.

Key Takeaways

  • Hypothyroidism in dogs results from low thyroid hormone production.
  • Common symptoms include lethargy, weight gain, and hair loss.
  • Treatment involves daily medication to replace the missing hormone.

Understanding Hypothyroidism

Hypothyroidism in dogs is a common endocrine disease caused by inadequate production of thyroid hormones, which regulate metabolism, energy levels, and overall health.

The Role of the Thyroid Gland

The thyroid gland, located in your dog’s neck, produces hormones that control metabolism. When functioning properly, it ensures your dog has adequate energy, a shiny coat, and a healthy weight. Without enough thyroid hormones, the body’s metabolic processes slow down, leading to various health issues affecting several organs and systems.

What Is Hypothyroidism?

Hypothyroidism occurs when the thyroid gland doesn’t produce enough hormones, leading to symptoms like weight gain, lethargy, and a dull coat. Other signs include hair loss, dry skin, slow heart rate, and increased cholesterol levels.

Differences Between Hypo- and Hyperthyroidism

Hypothyroidism is characterized by low thyroid hormone production, leading to a slowed metabolism. In contrast, hyperthyroidism involves excessive hormone production, speeding up the metabolism. While hypothyroidism is more common in dogs, hyperthyroidism can still occur, often due to thyroid cancer. Symptoms of hyperthyroidism include increased appetite, thirst, urination, and a rapid heart rate.

Recognizing the Signs of Hypothyroidism

Hypothyroidism in dogs can manifest through various symptoms such as lethargy, weight gain, and physical appearance changes. Early recognition of these signs can help you seek timely treatment.

General Symptoms

  • Lethargy: Noticeable reduction in energy levels.
  • Weight Gain: Occurs despite no change in diet or exercise habits.
  • Increased Susceptibility to Cold: Your dog may seek warm places more frequently.

Behavioral Changes

  • Less Playful and More Withdrawn: Reduced interest in activities.
  • Fatigue: Increased sleep and sluggishness.
  • Anxious or Depressed Demeanor: Changes in mood and interaction.

Physical Changes

  • Hair Loss: Typically starts on the trunk, back of the rear legs, and tail.
  • Dull and Brittle Coat: Skin can become flaky but usually isn’t itchy or red.
  • Weight Gain: Common without an increase in food intake.

Factors Contributing to Hypothyroidism

Several factors can contribute to hypothyroidism in dogs, including genetics, certain breeds being more at risk, environmental and lifestyle influences, and common underlying causes such as thyroiditis and thyroid atrophy.

Genetics and Breeds at Risk

Certain breeds like Golden Retrievers, Doberman Pinschers, and Irish Setters are predisposed to hypothyroidism. Large breed dogs are generally more susceptible. Genetic factors can lead to conditions like thyroiditis, where the immune system attacks the thyroid gland.

Environmental and Lifestyle Factors

Exposure to toxins, dietary deficiencies, and obesity can impair thyroid function. Ensuring a healthy diet and active lifestyle is vital for thyroid health.

Common Causes of Hypothyroidism

  • Thyroiditis: An autoimmune condition leading to thyroid gland destruction.
  • Thyroid Atrophy: Gradual wasting away of thyroid tissue due to genetic and environmental factors.

Diagnosing Hypothyroidism in Dogs

Early and accurate diagnosis of hypothyroidism in dogs requires a combination of physical examination and laboratory testing.

Physical Examination

A thorough physical examination involves checking for signs like weight gain, lethargy, hair loss, and dry skin. Palpation of the thyroid gland can reveal abnormalities.

Laboratory Testing

Blood tests measure thyroxine (T4) levels. Low T4 levels suggest hypothyroidism, but further tests, like free T4 and thyroid-stimulating hormone (TSH), confirm the diagnosis. Additional tests, such as urinalysis and autoantibody tests, help rule out other conditions and identify autoimmune thyroiditis.

Treatment Options and Management

Proper management of hypothyroidism in dogs involves medication, long-term care, and consistent monitoring.

Medication and Hormone Replacement

Hormone replacement therapy with levothyroxine supplements deficient thyroid hormones. Dosage varies based on the dog’s size, weight, and condition severity. Regular follow-ups with your veterinarian are necessary to adjust the dosage and monitor the dog’s response to treatment.

Long-Term Care

Daily medication is essential for life. Maintaining a healthy diet and regular exercise enhances overall well-being. Regular check-ups monitor the condition and treatment effectiveness.

Monitoring Treatment Efficacy

Regular blood tests measure thyroid hormone levels. Improved coat condition, energy levels, and weight stabilization indicate effective treatment. If symptoms persist or worsen, consult your veterinarian to reassess the treatment plan.

Living with Hypothyroidism

Living with hypothyroidism in dogs involves several adjustments to ensure they maintain a good quality of life.

Daily Life and Adaptation

Consistent routine and medication administration at the same time each day are crucial. Regular veterinary check-ups monitor hormone levels and adjust medication as needed. Observe your dog for any signs of lethargy, hair loss, or skin issues, and report them to your veterinarian promptly.

Diet and Exercise

A balanced diet supports overall health. High-quality, nutrient-dense dog food is essential. Regular walks and playtime help maintain a healthy weight and reduce the risk of obesity.

For managing hypothyroidism and supporting overall health, consider adding a high-quality probiotic supplement to your dog’s diet. Probiotics can help improve digestion and boost the immune system. Check out PawSafe® Probiotic Soft Chews for a trusted option

Support and Resources for Owners

Connect with your veterinarian for advice. Join support groups or online forums for shared experiences and tips. Reliable websites and veterinary care blogs provide up-to-date information on treatment options and lifestyle adaptations. Consult educational materials from veterinary hospitals for detailed guidance on medication schedules, dietary needs, and exercise routines.

Meet Your Experts

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Nick Peplow


Nick, co-founder of Pawsafe, is a certified pet care expert with a deep passion for enhancing pet and family well-being. With credentials in pet behavior, nutrition, and health, he shares his knowledge through informative blog posts. Nick’s dedication to pets is evident in his writing, inspired by his own Yorkie named Whiskey.

Nick, co-founder of Pawsafe, is a certified pet care expert with a deep passion for enhancing pet and family well-being. With credentials in pet behavior, nutrition, and health, he shares his knowledge through informative blog posts. Nick’s dedication to pets is evident in his writing, inspired by his own Yorkie named Whiskey.